The present invention relates to a track assembly that permits multi-axial movement of associated idler or “bogey” track support wheels and, in particular, to a two-piece frame assembly wherein several longitudinal stub-axles fitted between a drive frame and a multi-section sub-frame support a number of idler wheels to pivot laterally and/or multi-axially. Also disclosed are idler wheel rocker suspension axles mounted to the track frame from elastomer bushings, a removable belt tensioner assembly, a two-piece drive sprocket and an air bag torsion control assembly.
Track supported vehicles and equipment are designed for a variety of applications. The tracks enhance traction, distribute vehicle weight and reduce loading over an enlarged ground contact surface. Track systems of various designs are commonly used with military, commercial, farm, construction, personal (e.g. truck) and sport/leisure (e.g. snowmobiles and ATVs) vehicles. Tracks are also used in a variety of other applications with passive, un-powered equipment, for example, trailers, irrigation equipment and the like.
Depending upon the application, the track support frame and/or mounting system desirably provides some freedom to movement at the track assembly to compensate for the changing characteristics of the support terrain and/or enhance operating performance and/or track retention. A track assembly of applicant that provides torsion control is shown at U.S. Pat. No. 5,607,210. Another track assembly of applicant that is compatible with the subject invention is shown at U.S. Pat. No. 6,926,105.
U.S. Pat. No. 5,954,148 discloses a track assembly having a sub-frame that permits limited lateral rotation of a portion of the included idler wheels that are fitted to an intermediate idler sub-frame. An included support rod restricts the range of lateral rotation.
The present invention was developed to provide an improved track frame assembly wherein the idler or “bogey” wheels are able to pivot laterally to maintain uniform track contact and accommodate track flexion with changing terrain. In one construction, the idler wheels of a multi-section, longitudinal sub-frame are supported to laterally pivot from a supporting drive frame. The sub-frame sections, which contain several idler wheels mounted to rocker suspensions, are supported from pivot bearings fitted to an overlying drive frame.
In another track assembly, elastomer bushings are fitted to idler rocker suspension axles that support opposed sets of idler wheels. The resilient mounting of the suspension axles and contained idler wheels permit multi-axial movement of the wheels and axles to compensate for changes in the terrain and enhance track retention.
A tensioner that supports several idler wheels is also disclosed that detachably mounts as a nosepiece to a track frame (e.g. sub-frame or drive frame). The extension or retraction of included idler wheels selectively adjusts track tension and detachment of the tensioner facilitates track removal and replacement.
A multi-section drive sprocket/drive wheel/drum is also disclosed. The sprocket provides a removable center hub that is adaptable to a variety of vehicle mounts.
An air bag assembly is also mounted between the chassis and track frame to provide anti-torsion properties to control and limit rotation of the track frame.